It was the moment that brought a $200-million blockbuster to a screeching halt.

Robert Downey Jr. stood frozen in pain after leaping onto a platform of an oil tanker on the Wilmington, N.C., soundstage where “Iron Man 3” was shooting its fiery finale last year. The actor had made ambitious wire jumps for stunt scenes before, but this time was different. The impact of the landing left him with an ankle sprain so severe he was unable to walk for seven weeks.

“I was feeling a little bit invincible, I guess,” Downey said last week while making the promotional rounds for “Iron Man 3,” which rockets into theaters on May 3. “I checked it out, and I was like, ‘Oh, we got this.’ And we didn’t have it.”

When it comes to playing Tony Stark, the genius-billionaire-playboy-inventor whom Downey first brought to the screen in 2008’s record-breaking “Iron Man,” the Oscar-nominated actor could be forgiven for overreaching.

The character’s entire ethos is built on overreaching, believing there’s no situation or nemesis he can’t defeat with his winning combination of ingenuity, charm and resourcefulness. “Iron Man 3,” the first film from Marvel since the $2-billion worldwide success of “The Avengers,” finds Tony Stark feeling less invincible, however.

After saving the world from invading aliens, he’s stricken with bouts of insomnia and full-blown panic attacks — and that’s before a terrorist known as the Mandarin (Ben Kingsley) sends Stark’s sleek Malibu compound crumbling into the Pacific Ocean. Tony is forced to face the threat and protect lady love Pepper Potts (Gwyneth Paltrow) without the benefit of his superhero trappings.

“It’s an attempt on our part to have something worthy of Robert’s skills,” said director Shane Black, “which is to have a guy pushed to the edge endurance-wise and also psychologically to see someone thinking on their feet when they’re in trouble — real trouble, not the kind of smug champagne problems of a billionaire with infinite tech.”

Black penned the script with Drew Pearce, drawing from a well-known comic book story line involving a biological agent known as Extremis, which holds the power to cure illness and repair physical deformity — though not without serious side effects.

Franchise newcomer Rebecca Hall plays Maya Hansen, the scientist attempting to perfect the substance; Guy Pearce stars as Aldrich Killian, the entrepreneur who hopes to make a fortune from it. But it’s Kingsley’s role that has generated the most attention leading to the film’s release.

Robert Downey Jr., left, and director Shane Black on the set of “Iron Man 3.” (Zade Rosenthal / Marvel Entertainment)

Created by Stan Lee and designed by Don Heck, the Mandarin first appeared on the paneled page in 1964’s “Tales of Suspense” No. 50. A scientist and martial artist who derived his power from 10 rings that harness alien technology, the character proved an important foil for Stark, but Black has described the Mandarin as a “racist caricature.”

“In the old comics, he’s this sort of screeching Chinese warlord with his fist in the air all the time saying, ‘Fools! Come back when you have information, I’ll have your heads!’”

Moviegoers likely will be surprised by Kingsley’s performance. The character is now a warrior philosopher of indeterminate nationality with a driving hatred for America whose access to advanced weaponry poses great danger not just to Tony Stark but also to the U.S. government.

“If you go back to ‘Iron Man,’ it’s always been more grounded in sort of a geopolitical reality,” Black said. “When he’s with those troops in Afghanistan in the very first scene of ‘Iron Man,’ you think, ‘I get it. This is supposed to be real.’”

“Iron Man 3” marks the first feature from Black, 51, as either a writer or director since 2005’s noir-inflected caper “Kiss Kiss Bang Bang,” which starred Downey as an actor who throws in his lot with Val Kilmer’s gay private eye.

Black and Downey bonded during that production, and he credits the actor with lobbying for him to step behind the camera after Jon Favreau, who had directed “Iron Man” and 2010’s “Iron Man 2,” chose to turn his attention to other projects (though he does reprise his “Iron Man” role as bodyguard Happy Hogan).

Directing a superhero movie is never an easy proposition, but it’s a task made infinitely more difficult on a tight schedule. Downey’s injury forced Marvel to suspend filming for nearly two months while the star recuperated, and the post-production period was compressed to compensate for the lost days.

If early reviews are any indication, the rush to finish the film didn’t hurt the final product. Critics have praised the movie’s wit and sense of invention.

“I think Shane brought a lot of innovations to an already pretty edgy, cool franchise,” Downey said. “There’s such a groundswell of excitement about it, and I know that we earned it by the merits of what we created together.”